As different types of fuel systems are being developed to enhance the efficiency of internal combustion engines and allow for cleaner operation, manufactures are challenged to incorporate these new and improved fuel systems into an engine having a simplified design to minimize cost and complexity. One element that directly effects the efficiency at which an internal combustion engine operates is the device which controls the mixture of gas and air being fed into the engine for combustion. A design which is easy to manufacture yet meets or exceeds industry standards for gas fueled engines is currently sought by engine manufacturers.
Many different designs of gas/fuel mixers have been developed in order to enhance fuel efficiency. For example, U.S. Pat. No. 5,058,625 to Kaiser et al. discloses a valve for the intermittent introduction of fuel wherein the feeding means for supply fuel comprises inflow conduits extending into an intake passage and controlled by a rotating valve means which intermittently opens and closes the inflow conduits. Gas/air mixers such as those disclosed in Kaiser, however, are very complex and have different moving parts which could breakdown, increase the cost of repair and cause undesirable downtime. Moreover, the device disclosed in Kaiser does not appear to provide a structure that uniformly mixes gas with intake air. A non-uniform mixture could undesirably effect combustion.
A more simpler gas/air mixer design is shown in U.S. Pat. No. 5,150,690 to Carter et al. This design includes a flow control system having a gas-air mixer located in an intake air duct with a fuel diffuser tube extending across the intake air duct. The fuel diffuser tube has a plurality of openings through which the supplied fuel mixes with the air being drawn into the engine. This design, however, suffers from a similar deficiency discussed above with respect to Kaiser. Although Carter et al. discloses a gas/air mixer having a simpler design than that illustrated in Kaiser, the fuel diffuser tube extends across the center of the intake air duct, resulting in fuel being distributed only to the center of the air flow path which could affect the uniformity of the gas/air mixture at time of combustion.
An improved gas/air mixer design which appears to provide greater uniformity than the references discussed above is found in U.S. Pat. No. 4,872,440 to Green. This reference discloses an air/fuel mixing device for an internal combustion engine wherein the feeding means comprises circular apertures in an annular gas feeding device. The air/fuel mixer design of Green, however, is very complex in that the device has many different parts, some movable, which again creates a greater likelihood of breakdown resulting in costly repair and downtime. Furthermore, the complexity of the device increases manufacturing costs of the gas/air mixer and ultimately, the internal combustion engine.
A gas/air mixing device which appears to overcome the noted deficiencies of the above references is disclosed in U.S. Pat. No. 4,991,561 to Gerassimov et al. This reference is directed to a gas-air mixer including an inlet and outlet diffuser connected by a collar having uniformly shaped feeding channels which terminate in an annular channel around the diffusers connected to a gas supply. The feeding channels for the gas supplied through the annular channel are disclosed as slots which may be widened or narrowed to control the amount of gas mixed with the air in the inlet diffuser. Although Gerassimov et al. appears to disclose a gas/air mixer having greater simplicity and possibly greater gas/air uniformity than the patents discussed above, the reference includes moving parts which increase manufacturing costs and decreases the reliability of the device.
The inventors have recognized the need for a device having a simplistic design that improves the gas/air mixture by increasing its uniformity. In essence, increased uniformity results in optimal combustion and overall efficiency of the internal combustion engine. Moreover, a gas/air mixer having a simple design reduces manufacturing costs, decreases the chance of breakdown and prevents unnecessary downtime.